The present disclosure relates to xerographic printing systems, and, in particular, to a heater controller system for a fusing apparatus of a electrostatographic or xerographic printing system.
In electrostatographic printing, commonly known as xerographic or printing or copying, an important process step is known as “fusing.” In the fusing step of the xerographic process, dry marking material, such as toner, which has been placed in imagewise fashion on an imaging substrate, such as a sheet of paper, is subjected to heat and/or pressure in order to melt or otherwise fuse the toner permanently on the substrate. In this way, durable, non-smudging images are rendered on the substrate.
Currently, the most common design of a fusing apparatus as used in commercial xerographic printers includes two rolls, typically called a fuser roll and a pressure roll, forming a nip therebetween for the passage of the substrate therethrough. Typically, the fuser roll further includes, disposed on the interior thereof, one or more heating elements, which radiate heat in response to a current being passed therethrough. The heat from the heating elements passes through the surface of the fuser roll, which in turn contacts the side of the substrate having the image to be fused, so that a combination of heat and pressure successfully fuses the image.
In more sophisticated designs of a fusing apparatus, provisions are taken into account for the fact that sheets of different sizes may be passed through the fusing apparatus, ranging from postcard-sized sheets to sheets that extend the full length of the rolls. These designs provide for controlling the heating element or elements inside the fuser roll to take into account the fact that a sheet of a particular size of paper is fed through the nip. When a relatively large sheet of paper is passed through the nip, the heat is evenly distributed along the length of the fuser roll, while when a smaller sheet is passed through the nip, the heat is radiated only along the portion of the fuser roll corresponding to the sheet size, thereby aiding in the prevention of the fusing apparatus and the xerographic system as a whole from overheating.
However, such fusing apparatus designs for controlling heat radiation along the length of the fuser roll require increasing the mass of the fuser roll, which impacts warm-up response time, and individual controllers for each heating element, which impacts external subsystem electrical hardware costs. Moreover, these prior art fusing apparatus designs do not provide for heating portions or sections of the fusing apparatus in accordance with the dimensions of specific substrate sizes, such as 11″ long edge feed and A4 long edge feed performance, being fed through the fusing apparatus.
Accordingly, there exists a need for a heater controller system for a fusing apparatus which overcomes disadvantages in prior art fusing apparatus designs and includes for heating sections in accordance with the dimensions of specific substrate sizes being fed through the fusing apparatus.